Merton Council is set to join a mounting legal challenge against England’s exams regulator after it controversially refused to remark hundreds of downgraded GCSE results.

Following a consultation of the borough’s secondary schools, the council has agreed to pursue a judicial review against Ofqual after it put pressure on examiners to mark down English language papers to curb a rise in grade inflation.

Ofqual has stood by the new grading system and offered students the option to retake exams early, while the Education Secretary, Michael Gove, has refused to intervene in Ofqual’s decision.

The council’s cabinet member for education, Councillor Martin Whelton, said Merton would join the legal challenge started by Leeds City Council last month and supported by 10 local authorities in England, including Lewisham in south-east London.

Coun Whelton said: “I am appalled at the inaction of Ofqual in not remedying this gross injustice.

“We are working with a number of other authorities across the county on potential legal action to ensure we get redress for the many young people who have been so unfairly treated as a result of the changes.

“The Department of Education should have followed the example of the Welsh Assembly in ordering a remark.

“We believe the offer made by Ofqual of early resits was absolutely unacceptable and totally misses the point when the lives of many students have already been impacted.”

He said many students lost their places on college courses as a result of the grade changes after getting a D grade despite being predicted a C.

Across the borough, just under 60 per cent of students got five good GCSEs, including English and maths.

Coun Whelton said: “The downgrading had a significant impact – otherwise we would have been talking about getting the Merton figure up to 64 or 65 per cent. It’s made a big difference to schools’ performance.”

It is understood Raynes Park High School and Wimbledon College were among the borough’s schools most affected in terms of how many students got five A*-C grades (including England and maths).

Philip Wheatley, headteacher at Raynes Park High School, said their analysis found 60 students would have gained a C had the grade boundaries not been changed.

He said: "Most importantly, however, is the impact on individual students and their life chances that causes us concern and is a key factor in Merton’s possible decision to pursue a judicial review against Ofqual over the English GCSE.

"Overall, our students did extremely well amid a very difficult exam season and we remain immensely proud of their achievements."

Wimbledon College had 56 per cent of its students achieve this standard this summer, but it is estimated the college’s figure would have been in the low 70s had the results not been downgraded.

Chris Mallaband, the principal of St Mark’s Academy and chairman of Merton’s secondary heads group, said: “Merton schools have been hit by very unfair and late changes in the grade boundaries published by the exam boards.

“This means that the same standard of work that would have got a C in January would only get a D now in many, many cases.  You can see the impact in the results of some Merton schools. 

“It hit us [St Mark’s] but luckily was masked by the amazing improvement.”